The invention is based on a plug-in device.
The application DE 199 63 912.4-34 has disclosed a plug-in device with a unit plug and a socket part in which the unit plug has a knob that is disposed in a cutout of the socket part. Either a spring or a spring tab is required in order to secure the unit plug in the socket part.
DE 196 07 986 A1 has disclosed a tube coupling for two parts, where one part has a knob, which, in the connected state, is disposed in a cutout of the other part. The socket part has a spring, which presses the knob into the cutout. This spring is a bar that is stressed on one end and can therefore easily become mechanically fatigued.